Integration of magnetic and nonmagnetic measurements for current profile reconstruction in RFX

A crucial issue in magnetically confined plasmas characterized by relevant internal current redistribution, such as high beta and low field toroidal d evices, is the determination of their internal magnetic structure. The arti cle presents a method for the integration of magnetic and nonmagnetic measu rements in a model which considers a plasma described by stationary ideal m agnetohydrodynamic equilibrium equations, with toroidal and poloidal plasma currents represented by distributed discrete filaments and current sheets. The model also includes the massive conductors representing the vessel, th e shell, and the machine windings. The discrete current sets are determined by using as input data the total currents flowing in the plasma, in the wi ndings and in the vessel, as deduced by external integral magnetic measurem ents. The obtained filamentary current sets are then adjusted by imposing f urther constraints. One of the constraints is given by the set of local mag netic field measurements provided by external pickup coils. A further and m ore significant constraint is imposed by far infrared polarimeter, which gi ves an integral condition for each implemented measurement chord. The metho d is validated by using experimental data from the reversed field pinch Rev ersed Field eXperiment, and the results suggest that the current density di stribution is rather different from that usually predicted by conventional data inversion algorithms. (C) 2001 American Institute of Physics.